Waveguide couplers of the prior art are bulky, complicated and usually consist of loose parts which may be lost and do not lend themselves to rapid coupling and decoupling. Such prior art waveguide couplers are illustrated in the Microwave Components section of the 1980 English Electric Corporation catalog at p. 876, the waveguide clamp section of the 1983 Astrolab, Inc. catalog at p. 3222, and the 1983-1984 Airtron Microwave Components and Waveguide Catalog at pp. 38 and 39.
Other waveguide couplers are disclosed in U.S. Pat. Nos. 2,862,728; 3,076,948; 3,821,670; and 4,181,905.
U.S. Pat. No. 2,862,728 discloses a waveguide coupler that differs from the present invention in that: (a) It uses a multiturn engaging means having threads 7, as opposed to sleeve 31 of the instant invention, which engages in less than one revolution. As a consequence, the coupling and uncoupling is much slower. Furthermore, the threads are easily damaged. (b) It is not watertight. (c) It uses four latching dogs 3, rather than helical grooves and pins, to draw flanges together. As a result, wear and indentation of the dog contact points can gradually diminish the holding pressure and the integrity of the face contact essential for good electromagnetic performance. On the other hand, the present invention uses spring 35 to maintain a preselected unvarying face pressure which is not dependent upon the experience of the operator. (d) Polarization (circumferential) alignment is achieved with pins 14 engaging waveguide flange holes 22, which can become clogged, rendering engagement difficult. The present invention advantageously dispenses with these by achieving circumferential alignment with keys 27 and keyways 42 that are not part of the waveguide bodies themselves, and tend to be self cleaning every time the coupler is used. (e) One of the waveguide ends is exposed to mechanical damage, whereas in the present invention, both mating surfaces 17A, 17B are recessed.
The waveguide coupler disclosed in U.S. Pat. No. 3,076,948 has a pressure plate 1 which is loose (and thus can easily get lost in the field) and has external threads, which can be easily damaged, rendering the coupler useless. Backup plate 3 and nut 4 are not only loose and can move down the waveguide, but require substantial rearward axial clearance for engagement. The reference's multiturn threads require considerable torque for engagement (which can twist and deform the waveguide), make for a time consuming and inconvenient engagement, and also make for a variable face pressure, depending upon how much nut 4 is tightened. On the other hand, the present invention's spring 35 pressure gives a fixed coupling force, important for electromagnetic transmission. The waveguide faces of the reference device are not recessed as in the present invention, and thus can easily be damaged.
U.S. Pat. No. 3,821,670 discloses a waveguide coupler differing from that of the present invention in that: (a) It uses a multiturn engagement means, and therefore is relatively inconvenient to use. (b) Its engagement means uses threads which can be easily damaged. (c) It has loose parts which can get lost. (d) The face pressure is dependent on how much the engagement ring is tightened. This tightening torque can be considerble, and its transfer to the waveguide can damage the waveguide. (e) The mating faces of the waveguide are exposed, not recessed.
U.S. Pat. No. 4,181,905 discloses a waveguide coupler differing from that of the present invention in that: (a) It is not water tight. (b) It requires considerable axial space behind the flange for its operation. (c) The waveguide mating surfaces are not recessed and can be easily damaged during repeated coupling/uncoupling operations. (d) Circumferential alignment is achieved by screw heads engaging recessed holes which can be clogged by debris, rendering the coupler useless.
Secondary references are U.S. Pat. Nos. 2,462,370; 3,008,116; 3,351,886; 3,393,927; 3,750,087; and 3,835,443.
U.S. Pat. No. 2,462,370 discloses a connector for coupling a waveguide to a large cavity of an oscillator tube. It differs from the coupler of the present invention in that: (a) Many turns are needed for engagement. (b) It has threads which can be easily damaged, thus preventing coupling of the two members. (c) It connects waveguide to an oscillator tube as opposed to connecting two waveguides together. (d) It is not water tight. (e) The cavity is aligned with a key 10 that is part of the waveguide flange, which can undesirably lead to buildup of foreign matter in the vicinity of the waveguide. (f) One waveguide surface is exposed to damage because it is not recessed.
U.S. Pat. No. 3,008,116 discloses a coupler for connecting two multi-wire cables. No suggestion is made that this coupler can be used to couple waveguide sections. Water seal 154 is located in the shell 20, leaving the faces of the cable ends (blocks 24 and 80) in noncontacting proximity. This is not suitable for the coupling of waveguide. The present invention brings waveguide ends 17A, 17B together intimately at surface 51 for good electromagnetic performance, and simultaneously provides a water sealing contact 19 between said ends 17A, 17B themselves.
The reference device requires a large amount of pre-engagement of barrel 66 into shell 20 to help pins 16 engage without binding. The present invention does not require as much axial distance for engagement; it does not engage weak pins, but rather aligns keys 27 and keyways 42.
U.S. Pat. No. 3,351,886 shows a connector for multiwire cable. No suggestion is made that this device can be used for waveguide coupling. The reference device requires significant pre-engagement to align the two members before the pins engage the sockets. The axial distance required for engagement and withdrawal is therefore great. The present invention minimizes this axial distance.
U.S. Pat. No. 3,393,927 shows a "bayonet" coupler for aligning and drawing together separable electrical connectors, with no mention made of any applicability to waveguide.
U.S. Pat. No. 3,750,087 discloses a vibration resistant bayonet coupler for multipin electrical connectors. No suggestion is made of applicability to waveguide.
U.S. Pat. No. 3,835,443 discloses an RFI/EMI shield.